1. Field
This disclosure relates to wireless energy transfer, methods, systems and apparati to accomplish such transfer, and applications.
2. Description of the Related Art
Energy or power may be transferred wirelessly using a variety of known radiative, or far-field, and non-radiative, or near-field, techniques as detailed, for example, in commonly owned U.S. patent application Ser. No. 12/613,686 published on May 6, 2010 as US 2010/010909445 and entitled “Wireless Energy Transfer Systems,” U.S. patent application Ser. No. 12/860,375 published on Dec. 9, 2010 as 2010/0308939 and entitled “Integrated Resonator-Shield Structures,” U.S. patent application Ser. No. 13/222,915 published on Mar. 15, 2012 as 2012/0062345 and entitled “Low Resistance Electrical Conductor,” U.S. patent application Ser. No. 13/283,811 published on Oct. 4, 2012 as US 2012/0248981 and entitled “Multi-Resonator Wireless Energy Transfer for Lighting,” the contents of which are incorporated by reference. Prior art wireless energy transfer systems have been limited by a variety of factors including concerns over user safety, low energy transfer efficiencies and restrictive physical proximity/alignment tolerances for the energy supply and sink components.
One particular challenge in wireless energy transfer is control and tuning of the resonator structures and the power source to deliver controlled power to a load. In a wireless energy transfer system the source and device may move or change position. As the relative positioning of the system elements change the characteristic of the wireless energy transfer changes. Coupling between the source and device may change reducing the efficiency of energy transfer for example. Changes in the wireless energy transfer characteristics may change the power delivered to the load or cause unwanted fluctuations in the power delivered to a load at the device. A need exists for methods and designs for tunable wireless energy transfer system with tunable components to maintain efficient and constant energy delivery to a load at a device despite changes in the positioning, coupling, orientation, and the like of the system components.